1. Field of the Invention
The invention relates to a composition for fabricating a substrate, and more particularly to a composition for fabricating a substrate with high dielectric constant, low dielectric loss, and high flexibility, applied in PCB, IC substrate, or RF modules.
2. Description of the Related Art
Recently, with the increasing demands for multi-functional electronic products, electrical devices with flexibility have been widely developed to increase functions and convenience thereof.
Passive components with flexibility have been developed to increase the yield and reliability of electrical devices and improve electrical device integration employing the same, thereby facilitating the applications of soft or hard substrates.
U.S. Pat. Nos. 5,162,977 and 6,274,224 B1 discloses embedded capacitor technologies and structures. The capacitor comprises an electrical insulating layer formed from epoxy and barium titanate particles. However, the capacitor exhibits no flexibility and cannot be used in flexible substrates.
U.S. Pat. No. 5,739,193 discloses a polymeric composition having a temperature-stable dielectric constant, comprising a thermoplastic polymer, a high dielectric ceramic powder, and a second ceramic material. The polymeric composition has a high dielectric constant that only slightly varies with temperature.
U.S. Pat. No. 6,608,760 discloses a dielectric material which can serve as the material of printed wiring boards. The dielectric material comprises at least one organic polymer and at least one filler material. The dielectric substrate of this invention has a dielectric constant that varies less than 15% over a temperature range from −55° to 125° C.
U.S. Pat. No. 6,905,757 discloses a composition comprising resin and spherical dielectric powder and a built-in capacitor fabricated thereby. However, the built-in capacitor exhibits no flexibility.
U.S. Pat. Nos. 6,150,456 and 6,657,849 disclose a dielectric constant flexible film made of polyimide resin. JP Patent 338667 discloses a photosensitive polymer exhibiting flexibility. The polymer cannot be applied in a high-bandwidth electrical device due to inferior processing capacity.
U.S. Pat. Nos. 4,996,097 and 5,962,122 discloses a polymeric composition having a high dielectric constant made from a thermotropic liquid crystalline and a ceramic. The composition is not suitable for fabricating an embedded capacitor substrate by a printed circuit board process.
Therefore, it is necessary to develop a low dielectric loss, high dielectric constant and high flexibility dielectric material suitable for a soft printed circuit board process used for fabrication of an embedded capacitor substrate.